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<title>move-wide</title>
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<h1>move-wide</h1>

<h2>Purpose</h2>

<p>
Move the contents of one register-pair to another.
</p>
<p>
Note: It is legal to move from vN to either vN-1 or vN+1, so implementations
must arrange for both halves of a register pair to be read before anything is
written. 
</p>

<h2>Details</h2>

<table class="instruc">
<thead>
<tr>
  <th>Op &amp; Format</th>
  <th>Mnemonic / Syntax</th>
  <th>Arguments</th>
</tr>
</thead>
<tbody>
<tr>
  <td>04 12x</td>
  <td>move-wide vA, vB</td>
  <td><code>A:</code> destination register pair (4 bits)<br/>
    <code>B:</code> source register pair (4 bits)</td>
</tr>
<tr>
  <td>05 22x</td>
  <td>move-wide/from16 vAA, vBBBB</td>
  <td><code>A:</code> destination register pair (8 bits)<br/>
    <code>B:</code> source register pair (16 bits)</td>
</tr>
<tr>
  <td>06 32x</td>
  <td>move-wide/16 vAAAA, vBBBB</td>
  <td><code>A:</code> destination register pair (16 bits)<br/>
    <code>B:</code> source register pair (16 bits)</td>
</tr>
</tbody>
</table>

<h2>Constraints</h2>

<ul>
  <li>
    Both A+1 and B+1 must be valid register indices in the current stackframe
    (which includes A and B being valid).
  </li>
  <li>
    Register vB must be the lower half of a register pair (which excludes the
    case of it containing a reference).
  </li>
  <li>
    Both register vB and v(B+1) must be defined.
  </li>
</ul>

<h2>Behavior</h2>

<ul>
  <li>
    The value of register vB is moved to register vA, that is, vA' = vB.
  </li>
  <li>
    The value of register v(B+1) is moved to register v(A+1), that is, v(A+1)'
    = v(B+1).
  </li>
  <li>
    If register v(A-1) is the lower half of a register pair, then v(A-1)'
    becomes undefined.
  </li>
  <li>
    If register v(A+2) is the upper half of a register pair, then v(A+2)'
    becomes undefined.
  </li>
  <li>
    If A = B-1, then v(B+1)' becomes undefined.
  </li>
  <li>
    If A = B+1, then v(B)' becomes undefined.
  </li>
</ul>

<h2>Exceptions</h2>

<p>
None.
</p>

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